I've used that cast pulley on my last build and I really liked it, the pulley itself was pretty good but the assembly on it was terrible. I took it all apart and reassembled with red loctite and had to chase one hole that was cross threaded. It might just be the hub screwed crooked to the casting. I bet they just ram them in there without tighten the bolts in a cross pattern.
The other issue with these is that they aren't greased from the factory, they just have some light machine oil on them. I wonder if some of the bearing failures are from people that just slap them on without packing the bearing full of grease.
Welcome to mopeds, pretty much anything on a moped build has to be taken apart before you can use it, check all the torque, clean it up, reassemble with loctite, grease...
If it really is crooked, send it back to treats, they will take care of you. Mine runs true as heck. Also, I have had plastic pulleys that were super warped, and they don't roll belts, usually that is from misalignment. Make sure you are aligned at full variation and your engine mount spacer bushings are intact.